Light entering the eye has been discovered not only to facilitate vision, but also to cause various non-visual biological effects. For example, certain studies have revealed that environmental light is the primary stimulus for regulating circadian rhythms, seasonal cycles, and neuroendocrine responses. In some cases, and in particular with regard to biological responses to light, the environment can be controlled (e.g., to add more or less blue light) for various purposes. For example, light near the blue portion of the light spectrum can be used as a therapeutic tool in the treatment of sleep disorders and Seasonal Affective Disorders (SAD), such as “winter depression.” In such cases, the exposure to short wavelength light in the range of 440 to 480 nm can be controlled to suppress the melatonin secretion by the pineal gland and affect the circadian rhythm.
Conventional techniques for environmental controls, however, generally fail to consider the state and changes of state of a subject and/or the subject's environment. For example, a factory with a night shift might add more blue light to stimulate physiological response (i.e., to keep workers alert and productive). However, such environmental controls fail to consider the real-time response of the subjects to the changing environmental conditions.
Therefore, approaches are needed to address the problem of observing a particular subject's physiological conditions, and modifying the environmental conditions in response to the observed aspects. The present invention fulfills this need, among others.